1. Field of the Invention
The invention concerns the field of lighting and/or signaling, notably for motor vehicles. It more particularly concerns a lighting device with optical waveguides adapted to be installed in a headlight lighting module.
2. Description of the Related Art
A motor vehicle is equipped with headlights, or headlamps, intended to illuminate the road in front of the vehicle, at night or under low light conditions, by means of an overall light beam. These headlights, a left-hand headlight and a right-hand headlight, include one or more lighting modules each adapted to generate and to direct an intermediate light beam the combination of which forms the overall light beam.
These headlights can generally be used in two lighting modes: a first or “high beam” mode and a second or “low beam” mode. The “high beam” mode enables the road to be strongly lit to a great distance in front of the vehicle. The “low beam” mode produces lighting of the road that is more limited, although nevertheless offering good vision, without dazzling other road users. The two lighting modes, “high beam” and “low beam”, are complementary and a change is made from one to the other as a function of traffic conditions. Switching from one mode to the other may be effected manually, the driver deciding when to switch over, or automatically, as a function of the detection by appropriate means of conditions requiring such a change of lighting mode.
There nevertheless exists a requirement, in the motor vehicle field, to be able to illuminate the road ahead in “partial road lighting mode”, namely to generate in a high beam one or more dark regions corresponding to the locations of vehicles approaching in the opposite direction or vehicles traveling in front, so as to avoid dazzling other drivers, while at the same time illuminating the greatest possible area of the road. Such a function is referred to as an adaptive driving beam (ADB) or “selective beam” function. This kind of ADB function consists on the one hand in automatically detecting a road user liable to be dazzled by a lighting beam emitted by a headlight in high beam mode and on the other hand in modifying the contour of this lighting beam so as to create a shadow region at the location of the road user who has been detected. The ADB function has multiple advantages: user friendliness, improved vision compared to lighting in low beam mode, improved reliability for the change of mode, greatly reduced risk of dazzle, safer driving.
Selective beam producing lighting modules are known in which optical waveguides are disposed side-by-side, each being illuminated by a respective light source so that the light beam at the exit of the module is divided into contiguous segments that can be turned off or turned on as a function of instructions resulting from the detection of a vehicle nearby.
The shape and the arrangement of the waveguides relative to one another in a module of a headlight must be very accurate, on the one hand to be able to produce a smooth and homogeneous intermediate beam at the exit from the module when all the segments are turned on and on the other hand to be able to offer an intermediate beam complementary to the intermediate beam produced exiting the other headlight.